Small-scale oilseed processing
Practical Action
To determine whether small scale processing is likely to be economic it is important to first
investigate the local situation and regulations.
Raw material supply
Clearly there must be sufficient raw material available locally. One factor that will influence the
viability of the enterprise will be the amount of credit needed to purchase a stock of seed. The
enterprise should aim to keep the minimum stock of seed but always have enough to continue
operating throughout the year. This requires considerable working capital.
Health and safety
As oil processing is classified as a food processing enterprise it will be subject to local
legislation. Care should be taken that standards are understood and met. The particular problem
of aflatoxins will require attention. Aflatoxins are natural poisons produced by certain moulds
that grow on seeds and nuts. They are of considerable concern to oil seed processors. The growth
of aflatoxin producing moulds can be prevented by correct drying and by preventing moisture
pickup by seeds in storage. It is most important that those considering establishing an edible oil
enterprise should be able to recognise aflatoxin producing moulds and understand how to
correctly select and store raw materials. If aflatoxin is present very little passes to the extracted
oil, the majority will be found in the cake remaining after extraction. Aflatoxin-contaminated
cake presents a real danger if incorporated in livestock feeds. As aflatoxin is difficult to remove
good practice is essential to prevent any mould growth and so prevent problems.
Not all oilseed crops are suitable for processing at a small scale, the most common types that
are suitable include, sunflower, sesame, and mustard seed. Typical oil contents of seeds are
shown in Table 1.
Common oilseeds
Oil content %
Use
Castor 35 - 55
Paints, lubricants. Non-edible as it
contains ricin which is highly toxic.
Cotton 15 - 25
Soaps. Non edible as it contains
gossypol which is a toxic. Sophisticated
equipment can be used to remove
gossypol.
Linseed/flaxseed 35 - 44
Paints, edible nutritional supplement.
Rape/canola/mustar 40 - 45
Cooking, biodiesel.
d
Sesame 35 - 50
Cooking.
Sunflower 25 - 40
Cooking, biodiesel.
Less common
Oilseeds
Neem 45 - 50
Soap, cosmetics, insecticides.
Karanja 27 - 39
Insecticides.
Pumpkin 34 - 54
Lighting, edible.
Avocado 3 - 30
Cooking, edible, cosmetics.
Niger 38 - 50
Cooking, medicinal, soap, paint.
Table 1 Oils and their uses
In many cases the crude extracted oil is not suitable for human consumption until it has been
refined to remove undesirable free fatty acids that taste rancid, dark colours, waxes and toxic
components. Refining involves considerable extra equipment costs. The most suitable oils for
small and medium scale extraction are those that need little or no refining eg. mustard, sesame,
and sunflower.
Methods of extraction
Five common methods are used to extract oil:
2